Visible light photoactivity of Polypropylene coated Nano-TiO2 for dyes degradation in water

Abstract

The use of Polypropylene as support material for nano-TiO2 photocatalyst in the photodegradation of Alizarin Red S in water solutions under the action of visible light was investigated. The optimization of TiO2 pastes preparation using two commercial TiO2, Aeroxide P-25 and Anatase, was performed and a green low-cost dip-coating procedure was developed. Scanning electron microscopy, Atomic Force Microscopy and X-Ray Diffraction analysis were used in order to obtain morphological and structural information of as-prepared TiO2 on support material. Equilibrium and kinetics aspects in the adsorption and successive photodegradation of Alizarin Red S, as reference dye, are described using polypropylene-TiO2 films in the Visible/TiO2/water reactor showing efficient dyes degradation.

Kinetic Model for Simultaneous Adsorption/Photodegradation Process of Alizarin Red S in Water Solution by Nano-TiO2 under Visible Light

“…In this case, the maximum ARS adsorption corresponds to a saturated layer of dye molecules on the TiO 2 surface that cannot contribute to an additional incorporation of other molecules. In contrast, the multilayer adsorption process according to the Freundlich isotherm occurs on [PP@TiO 2 ] A [22].…”

“…The first is represented by the decrease of ARS concentration in the solution due to adsorption on PP@TiO 2 surface. The absorption of ARS is proved that occurs with a process described by the first order kinetic constant k 1 expressed by the equation lnrpq e ¡ q t q{q t s ¡k 1 t, where q t is the amount of adsorbed dye at time t and q e is the equilibrium concentration [22].…”

“…The second process is represented by photodegradation of ARS, process that occurs with a rate described by the first order kinetic constant k 2 expressed by the equation ln pC{C 0 q ¡k 2 t [22,23] where C 0 is the initial concentration of ARS and C the concentration of dye at t time.…”

“…The obtained kinetic results were discussed and compared with those derived from the previous study regarding separated steps of adsorption and photodegradation [22], and a kinetic model which described the overall process in an adequate way has been proposed. In this study, in order to optimize and clarify the total photocatalytic mechanism of ARS as target pollutant, two commercial types of nano-TiO 2 such as Anatase and Aeroxide P-25 coated on polypropylene supports (PP@TiO 2 ) were used, and the simultaneous adsorption and visible light photodegradation of dye from water solution were studied.…”

“…In this study, in order to optimize and clarify the total photocatalytic mechanism of ARS as target pollutant, two commercial types of nano-TiO 2 such as Anatase and Aeroxide P-25 coated on polypropylene supports (PP@TiO 2 ) were used, and the simultaneous adsorption and visible light photodegradation of dye from water solution were studied. The obtained kinetic results were discussed and compared with those derived from the previous study regarding separated steps of adsorption and photodegradation [22], and a kinetic model which described the overall process in an adequate way has been proposed.…”